High speed turbine assembly for dental handpieces and the like

Abstract

A high speed turbine handpiece includes a housing with a turbine wheel chamber and a flow passage for air terminating in a nozzle opening on the periphery of the turbine wheel chamber as well as a discharge passage from the chamber to the exterior of the housing. An integrally formed turbine wheel in the chamber has a hub with two axially spaced sets of vanes extending about its circumference with the blades of one set circumferentially offset from the blades of the other set. The nozzle is aligned with the axial spacing or channel between the sets of vanes and is dimensioned to overlap the adjacent edge portions of the vanes so that air entering through the nozzle impinges on both sets of vanes.

Having thus described the invention, I claim: 
     
       1. In a high speed turbine handpiece for effecting rotational motion of a tool bit engaged therein, the combination comprising: A. a housing having an inlet fitting for coupling to a source of air under pressure, a turbine wheel chamber, a flow passage between said fitting and a nozzle opening on the periphery of said turbine wheel chamber, and a discharge passage from said turbine wheel chamber extending from a point spaced from said nozzle to the exterior of said housing;   B. a turbine wheel rotatable in said chamber and having a hub and two axially spaced apart sets of vanes extending about the circumference thereof and defining a generally annular channel therebetween, said wheel being integrally formed with the blades of one set being circumferentially offset from the blades of the other set, said nozzle being aligned with said annular channel defined by the axial spacing between said sets of vanes and being dimensioned to overlap the adjacent portions of said vanes so that air entering through the nozzle impinges directly upon the vanes of each of said sets;   C. a shaft engaged with the hub of said turbine wheel for rotation therewith; and   D. tool bit engaging means on said shaft for engaging a tool bit for rotation therewith.   
     
     
       2. The handpiece of claim 1 wherein the trailing edges of said vanes are concave and the faces thereof extend generally radially, and wherein the leading edges of said vanes are generally planar and inclined secantally at a relatively shallow angle to intersect the root of the face of the adjacent vane. 
     
     
       3. The handpiece of claim 2 wherein the center for the radius of the curve defining said concave faces is located at a point spaced from the adjacent end of the of the vane about one-fourth of the total distance between the axial ends of the vanes. 
     
     
       4. The handpiece of claim 1 wherein said vanes of each set are equiangularly spaced, and the vanes of the two sets alternate to define equiangular spacing of the vanes of said two set about the axis of said wheel. 
     
     
       5. The handpiece of claim 4 wherein said equiangular spacing of each set is 60° and of the two sets is 30°. 
     
     
       6. The handpiece of claim 1 wherein the peripheral edges of said vanes are of a thickness substantially less than the width of said nozzle. 
     
     
       7. The handpiece of claim 1 wherein said shaft comprises a hollow, generally cylindrical spindle, and wherein said hub has a bore of generally circular cross section extending therethrough dimensioned to seat snugly upon said spindle. 
     
     
       8. The handpiece of claim 7 wherein said tool bit engaging means is a resiliently expansible chuck means coaxial with and disposed within said bore of said spindle, and wherein said handpiece includes bit releasing means slidably seated within said turbine wheel hub and spindle bore and actuatable externally of said housing to press against the shank of an associated tool bit seated in said chuck for disengaging the bit therefrom. 
     
     
       9. The handpiece of claim 1 wherein said discharge passage extends generally radially from a point in the circumference of said turbine chamber and thereafter generally axially in said housing for discharge of the air at the rear end thereof.